It is well known to provide dispensers for releasing substances such as bleaches, cleaners or disinfectants gradually or intermittently into toilet bowls. These usually take the form of a solid block adapted to be held near the rim of the bowl. Recently more complex arrangements wherein the substance is in liquid or gel form have also been developed. One problem with all of these arrangements is that the substance is dispensed only at one part of the rim. This means that the substance may not adequately be dispersed around the whole bowl, for example to provide an adequate cleaning or bleaching effect on all visible surfaces.